Derek McInnes has told Ryan Jack his time will come after missing out on the chance to face England at Wembley.

The Aberdeen midfielder received his first call-up to the senior squad for the clash with Croatia in June but is back in the Under-21s.

They’ll face the Auld Enemy at Bramall Lane on Tuesday, 24 hours before the top teams square up and Under-21 boss Billy Stark wants his strongest possible side for the England clash, with Jack in line to be named skipper.

The 21-year-old started the domestic season with an impressive display in Dons’ 2-1 win against Kilmarnock.

McInnes is convinced he will be a full international regular before long and said: “It’s a great achievement for the lads to get called up for the Under-21s again. Although I was a little bit disappointed for Ryan not to be in the senior squad.

“It would have been some experience being part of the Scotland squad at Wembley.

“But I guess you could argue he will probably learn more playing the England Under-21s than sitting on the bench for the full side. His time will come. Ryan got a great boost from being picked for the squad against Croatia.

“You could see the lift it gave him and he came back from pre-season with his chest out and a lot of confidence. He is a quietly-determined lad and he has a great attitude.

“I am sure he might have thought he might be in with a chance of Wembley but I have no doubt if he keeps working the way he has been he’ll be a regular in the senior side one day.

“You could even see it on Saturday, even though it is still early days. He was in the middle alongside experienced players in Barry Robson and Willo Flood.

“He didn’t look out of place and it will only help his game being able to watch and learn from the likes of Barry Robson.

“It’s great that he has a versatility and can play in a lot of positions but I see a big future for him in midfield.”

McInnes is delighted with Clark Robertson’s progress after handing the youngster the left-back role.

He is in line for his sixth Under-21 cap after recovering from the disappointment of injuring his knee just days before his first call-up in April 2012.

McInnes said: “Clark has come back from an injury last year and made himself into a regular with the Under-21s.

“It’s often overlooked that he is still only 19, because he has played so many games in the top division.

“He is a talented lad and he still has a lot of developing to do as well, which augurs well for the future.”

McInnes, meanwhile, has challenged Declan McManus prove during his loan spell at Alloa that he is ready for his shot at Dons’ first team.

The prolific youth striker last week joined Paul Hartley’s Wasps on a six-month deal.

The 19-year-old made an impressive debut at the weekend as they dumped Peterhead out of the League Cup at Balmoor.

McInnes has received rave reports from youth boss Neil Simpson who has watched McManus blaze a goal trail in the Under-20s league.

The Dons hitman, top scorer for the last two seasons, has been tipped to break into the top team this season.

“But his route to the starting line up has been blocked by talisman Niall McGinn, Calvin Zola, Scott Vernon and Josh Magennis.

McManus, who was denied the chance of a loan deal at Dundee in January, is out to make the most of his chance at Alloa and McInnes is convinced the Dons will get an even better prospect back in the New Year.

He said: “We felt it was a good level for him and a good gauge for us to see where he is.

“He’s scored 20-odd goals a season for the under 20s in the last couple of years and I have no doubts he would do the same this year, but does he really need to?

“I wouldn’t say he is a regular starter for the first team quite yet so it’s good for him to go out and prove himself against good opposition in the First Division.

“Hopefully he will prove himself and come back to us with confidence to kick on and try to get in the team in January.

“It’s a good move for everyone concerned and I am sure it will work out.